I was on maternity leave for all of 2021, my husband worked. Can I claim childcare expenses for my older child’s part time daycare fees even though I was not working?

Yes. Since you would have a lower net income than your spouse, you can claim the childcare expenses on your return. 

Information on claiming childcare expenses, as per the Canada Revenue Agency (CRA):
Line 21400 - Who can claim child care expenses? - Canada.ca
Line 21400 - What payments can you claim? - Canada.ca

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