It really depends on the status of your previous fiscal years as well as whether or not the customer accounts were adjusted. You could always reopen the fiscal periods but in general this is very ill-advised because I would think you would have already finalized that fiscal year (2017?) for tax purposes and balanced your receivables and bank accounts. If you already credited the customer accounts, then you need to research how it was done and offset it in GL probably in the current fiscal year. If everything was already offset in AR and GL in previous years and the bank account reconciled, then it would have to be some fairly significant amounts to devote that much time to the research required to work out what happened 3-4 years ago.

GAAP rules generally apply to this type of scenario and indicate you should not make adjustments to closed fiscal years. If you are a publicly traded company, SOX rules probably apply and there might be an issue of legality. Direct the question to your auditor and determine their opinion on modifying a previously closed fiscal year (hold the phone away from your ear and/or don't be offended by all caps).

If you are still committed to posting new payments, you can always make notations with the entry then date and post the transactions in the current fiscal year. The amounts had to have been offset in the prior year(s) in GL or AR if you reconciled, so you could reverse that logic. You would also need to reconcile the bank balance(s) and potentially customer statements. The days to pay and other stats on those customers will be incorrect which you would just have to account for in credit reviews or with the customer.

It really depends on the status of your previous fiscal years as well as whether or not the customer accounts were adjusted. You could always reopen the fiscal periods but in general this is very ill-advised because I would think you would have already finalized that fiscal year (2017?) for tax purposes and balanced your receivables and bank accounts. If you already credited the customer accounts, then you need to research how it was done and offset it in GL probably in the current fiscal year. If everything was already offset in AR and GL in previous years and the bank account reconciled, then it would have to be some fairly significant amounts to devote that much time to the research required to work out what happened 3-4 years ago.

GAAP rules generally apply to this type of scenario and indicate you should not make adjustments to closed fiscal years. If you are a publicly traded company, SOX rules probably apply and there might be an issue of legality. Direct the question to your auditor and determine their opinion on modifying a previously closed fiscal year (hold the phone away from your ear and/or don't be offended by all caps).

If you are still committed to posting new payments, you can always make notations with the entry then date and post the transactions in the current fiscal year. The amounts had to have been offset in the prior year(s) in GL or AR if you reconciled, so you could reverse that logic. You would also need to reconcile the bank balance(s) and potentially customer statements. The days to pay and other stats on those customers will be incorrect which you would just have to account for in credit reviews or with the customer.